Saint Beast: Ikusen no Hiru to Yoru Hen should be the side story of Saint Beast and not the other way around.

Then I wondered if anyone knew how the new series Saint Beast - Kouin Jojishi Tenshi Tan relates to the others...
And what kind of relation do you choose if you know it's related in some way, but not exactly sure how...should I use "other"?

EDIT:
Can some mod please correct the relations of these series, it really bothers me when looking at my up2date sequels page...